ULTRASTRUCTURAL-CHANGES IN GLOMERULAR EPITHELIAL-CELLS IN ACUTE PUROMYCIN AMINONUCLEOSIDE NEPHROSIS - A STUDY BY HIGH-RESOLUTION SCANNING ELECTRON-MICROSCOPY

Ultrastructural changes in the podocytes were studied during the devel opment of, and recovery from, acute puromycin aminonucleoside (PAN) ne phrosis using high-resolution scanning electron microscopy (hrSEM) and transmission electron microscopy (TEM). In the process of development of PAN nephrosis, four types of early structural changes were observe d before total loss of foot processes: formation. of cytoplasmic blebs , masking of filtration clefts, flattening of foot processes, and retr action of foot processes. The masking of filtration clefts visualized by hrSEM corresponded to the multiplication of slit diaphragms and adh esion of foot processes in the TEM findings, and preceded retraction o f the foot processes. Changes of podocyte configuration were produced. Recovery from this change of podocyte configuration began as islands of podocyte interdigitation, and was proceeded by expansion of the isl ands. During recovery, the primary processes were re-established eithe r by retraction or perforation of the thin cytoplasm after the formati on of foot processes. We conclude that loss of foot processes begins w ith the masking of filtration clefts. Recovery from the change in podo cyte configuration begins with the formation of new foot processes.